title: Homoeologous gene silencing in tissue cultured wheat callus.
abstract: BACKGROUND
  In contrast to diploids, most polyploid plant species, which include the hexaploid bread wheat, possess an additional layer of epigenetic complexity. Several studies have demonstrated that polyploids are affected by homoeologous gene silencing, a process in which sub-genomic genomic copies are selectively transcriptionally inactivated. This form of silencing can be tissue specific and may be linked to developmental or stress responses.
  
  
  RESULTS
  Evidence was sought as to whether the frequency of homoeologous silencing in in vitro cultured wheat callus differ from that in differentiated organs, given that disorganized cells are associated with a globally lower level of DNA methylation. Using a reverse transcription PCR (RT-PCR) single strand conformation polymorphism (SSCP) platform to detect the pattern of expression of 20 homoeologous sets of single-copy genes known to be affected by this form of silencing in the root and/or leaf, we observed no silencing in any of the wheat callus tissue tested.
  
  
  CONCLUSIONS
  Our results suggest that much of the homoeologous silencing observed in differentiated tissues is probably under epigenetic control, rather than being linked to genomic instability arising from allopolyploidization. This study reinforces the notion of plasticity in the wheat epi-genome.
authors.affiliation: Department of Pharmacy, University Nottingham, NG7 2RD, UK. andrew.bottley@nottingham.ac.uk
authors.forename: Andrew
authors.initials: A
authors.lastname: Bottley
authors.forename: Natalie H
authors.initials: NH
authors.lastname: Chapman
authors.forename: Robert M D
authors.initials: RM
authors.lastname: Koebner
mesh_terms: D002454:Cell Differentiation / Q000235:genetics; D002478:Cells, Cultured; D019175:DNA Methylation; D018076:DNA, Complementary / Q000235:genetics; D020224:Expressed Sequence Tags; D020869:Gene Expression Profiling; D020868:Gene Silencing; D017343:Genes, Plant; D018807:Polymorphism, Single-Stranded Conformational; D011123:Polyploidy; D018749:RNA, Plant / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014908:Triticum / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D018749:RNA, Plant